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Mash conversion, what reduces it?

Post #1 made 14 years ago
by Lemon
My most recent BIAB suffered from what I can only deduce is low conversion in the mash.
I have mashed using this single infusion method for a half dozen times and gotten good, approx. 75%, efficiency, but on this occasion, Diabolical = 59%.

Recipe,
Aus Ale - 4.78kg
Cara hell - 0.251kg
Wheat malt - 0.500kg

strike 67C 37l
90 min mash
no mash out
90 min mash temp. 64C (I normally aim for/acheive 65C)

Target OG was 1050, actual 1040 post boil (nb. new stand and burner mods meant boiloff was significantly higher than planned only got 21l into the fermenter. Left about 2l in the kettle.

Can anyone add anything to reduce my confusion? What could be causing this?

grain?
mash temp?
water chemistry? I live in Newcastle Aus, hasn't been a problem to date.

Yours in confusion :dunno:

Lemon
    • SVA Brewer With Over 100 Brews From Australia

Post #2 made 14 years ago
by iijakii
I try to approach these things from an Occam's razor point of view:

You didn't stir well enough and had many dough-balls, or your grain crush was atrocious.

Do you think either of these are likely?

Post #3 made 14 years ago
by Lemon
Iijakii,
Short answer, yes.
I got LHBS to mill, best I can say is, I specified same as normal and it "looked" normal.

I normally stir to begin with and then leave for 90min, so same same. Answers stiring and dough ball questons.

What I do need to add is that, the sweet liquor, at the end of the mash, 90 min, was not clear but cloudy, I took this as anecdotal evidence, still starchy?

Lemon
    • SVA Brewer With Over 100 Brews From Australia

Post #4 made 14 years ago
by stux
Might be,

is it the first time you've used wheat?

the mashout increases efficiency, and it specifically helps with "sticky" grains, like wheat which you can have trouble sparging...

when you pull the bag, you're actually sparging the grain as the water runs past it, and this is more effective at 75C than a rather cool 62C, or whatever you were at when you pulled the bag... its purely because the wort is thinner at a hotter temperature.

In future, if you're start of boil gravity is less than expected, feel free to go and re-sparge your grain bag to get a few more % out ;)

Also, if you're coming in under your end of boil because you've boiled off more, there's nothing that says you can't add boiling water during the boil!

PS: if you're that way inclined, my Maxi-BIAB calculator will help you to calculate updated start and end of boil figures, as well as various additions based on actual achieved efficiencies
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III

5/7/12

Post #5 made 14 years ago
by Lemon
Stux,
while not the first time I've used wheat, it is certainly the most wheat I've used, by at least double.

Hmmmmm............mashout, seems like it's time!

Lemon
    • SVA Brewer With Over 100 Brews From Australia

Post #6 made 14 years ago
by PistolPatch
Don't read too much into a weird reading on one brew Lemon. The problem could have been something as simple as incorrectly weighed grain. Your prior brews have been fine so I wouldn't give this one another thought.

:peace:
PP
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Post #8 made 14 years ago
by PistolPatch
Don't tell hashie! That bastard doesn't stir at all and still gets great efficiency :lol:

I think you'll be fine on your next brew. If you have the means though, for your own piece of mind, try and weigh your grain bill before you mash in. I, and every other brewer who has their own scales has stuffed up sometimes so it is silly to think retailers will never make an error and that you won't be the recipient of such an error twice in a row! Stranger things have happened!

:luck:
PP
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Post #10 made 14 years ago
by Lemon
Something has just occurred to me!!!!!

What if, in my impatience, I had not let the wort sample cool down sufficiently when I took my OG reading with the hydrometer?
Say the wort temp was in the 30s C.

I'm guessing the 1040 SG would in fact be something like 1045+

Hmmmmmm..............another good reason not to rush into anything controversial like stirring.

Thanks for your help.

Lemon
    • SVA Brewer With Over 100 Brews From Australia

Post #11 made 14 years ago
by PistolPatch
You're absolutely right Lemon. This is one of many things that can go wrong with the taking of measurements.

Most hydrometer jars are useless for a start - far too narrow* and this is even before we get into temperature adjustments.

When you are starting out, I think you should measure at every opportunity as doing this will obliterate your confidence in measurements much faster. You might think this last sentence is a bit of comedy but I am actually deadly serious.

I have no idea of how many brews I have done or been active in but it has been a lot and I can still only offer other brewers averages.

What I do know now are two things...

1. With a good recipe and a good thermometer (in other words, a few glass thermometers) you will, assuming things have been weighed somewhat correctly and you know the basics, get a great beer.

2. Taking measurements can also be a bit of fun. I often avoided measurements as I didn't want to waste 200 mls of precious wort (*200mls is about what is required in a decent hydrometer jar) with readings that could not be returned to the wort. Silly stuff! I'm more happy now taking the extra measurements but sometimes they make no sense the next day if I have had brewing company :lol:.

I like measuring trub as well. This requires a lot of dedication but I am always amazed at the range. WTF?

:think:
PP
Last edited by PistolPatch on 28 Feb 2011, 21:24, edited 5 times in total.
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